1. Field of the Invention
The present invention relates to the field of communications. More particularity, the present invention relates to a stereoscopic television system producing images capable of being observed in three-dimensions on a television monitor.
2. Description of Prior Art
Modern television is based on well-established technology of converting light from a still or moving person, object, scene (hereinafter generally referred to as an "image source") into electrical signals. Such conversion is accomplished by a camera unit which subsequently transmits these electrical signals for (i) reconversion into visual images displayed on a television monitor screen or (ii) storage for later reconversion.
Various types of stereoscopic television systems have been proposed for providing a motion picture film, television broadcast and the like to be displayed in three-dimensions on a television monitor screen. These stereoscopic systems generally included a single camera capturing (e.g., converting visual images into information used for video display) two slightly displaced images of the image source. The slightly displaced images are simultaneously displayed on a single screen for observation by a viewer such that a left eye of the viewer observes only one of the two slightly displaced images while the viewer's right eye observes only the other displaced image.
One such conventional stereoscopic system is disclosed in U.S. Pat. No. 4,281,341 to Byatt. This stereophonic system discloses a transmitting subsystem including a single camera unit having a complicated stereoscope, consisting of a pair of lenses, mirrors and polarizers, which produces a composite image based on two images received through the pair of lenses. A liquid crystal cell is controlled by a frame rate switch which activates the liquid crystal cell on alternate frame periods. This allows the liquid crystal cell to exist in either (i) a "horizontal" polarization state allowing one of the images to propagate through an additional polarizer and into the single camera or (ii) a "vertical" polarization state allowing the other image to propagate as described above. The additional polarizer is used for filtering purposes.
However, a primary disadvantage encountered by this conventional stereoscopic system, as well as many other prior stereoscopic systems, is that it requires complete redesign of the camera unit. The cost to redesign a camera unit in order to implement this system would likely be prohibitive to local and privately-owned television stations. Another apparent disadvantage is that this conventional stereoscopic system polarizes light from the image source resulting in a poorer image quality due to inefficient light transmission (approximately 80% efficiency) to the camera image screen from the polarizers, placed between the image source and the camera image screen.
Previously, there has been efforts to provide a stereoscopic system utilizing a pair of camera units as shown in U.S. Pat. No. 4,122,484, issued to Tan. This stereoscopic system discloses a transmitting subsystem including a pair of camera units aimed horizontally at different angles to represent a certain viewpoint of a viewer. Each of the camera units individually produces an independent video signal, wherein both video signal are processed by a signal processing device to provide a composite video signal. The composite video signal is transmitted to a receiving subsystem including a customized three-dimensional television monitor having a projection display tube utilizing light polarizers or light-selecting filters in combination with a reflecting mirror.
Similar to the disadvantage associated with the stereoscopic system disclosed in Byatt, this stereoscopic system encounters the disadvantage in requiring complete redesign of standard television monitors. The implementation of this stereoscopic system would require a large capital investment by television manufacturers.
Hence, it would be advantageous to create a three-dimensional stereoscopic television system which does not require substantial modification of either a camera unit within a transmitting subsystem of the television system or a television monitor within a receiving subsystem of the television system.